Questions tagged [moons]

For questions pertaining to natural satellites, such as our own Moon.

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120 votes
7 answers
43k views

How would having multiple moons affect tides?

We know that planets can have multiple moons, sometimes quite a few (like Jupiter). Assuming that a planet with several moons were habitable in the first place and has significant oceans (greater ...
Monica Cellio's user avatar
101 votes
6 answers
23k views

Would a Moon made of water pose a threat to Earth during eclipses?

Is a moon made entirely of water possible? Could a planet made completely of water exist? I was inspired by the above questions to ask the following: Assume that our current Moon is replaced ...
chasly - supports Monica's user avatar
63 votes
20 answers
13k views

What could a self-sustaining lunar colony slowly lose that would ultimately prove fatal?

I've got a lunar colony that was set up to be self-sustaining before a collapse of life on Earth. The colony has survived on its own for several thousand years through a period of technological ...
aaronius's user avatar
  • 621
63 votes
16 answers
9k views

Speedrun to the moon in one lifetime?

Imagine you have a large population of adolescent humans (as large as you need) on a completely uncultivated Earth, initially containing no artificial structures whatsoever, only natural resources. ...
Franklin Pezzuti Dyer's user avatar
52 votes
7 answers
11k views

Can I use a trebuchet to launch satellites into space from a lunar colony?

I've got a lunar colony that struggles to obtain resources, so they're looking for ways to launch satellites into orbit without using up a bunch of rocket fuel. One plucky engineer has suggested ...
Dubukay's user avatar
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50 votes
4 answers
6k views

Moons of Moons of Moons

My question is simple: How many nested moons are physically possible? If our moon had a moon, that would be a nesting of 1. I'm assuming it's easily possible for a really big moon to be orbiting a ...
Varrick's user avatar
  • 3,683
41 votes
3 answers
12k views

Habitable moon of a gas giant: working out the sizes and distances

I am attempting to create fictional, stable P-Type binary system, featuring a gas giant in a stable orbit, with a habitable Earth-like moon. “Is a Jupiter-sized planet plausible in a habitable zone?” ...
platypus-rising's user avatar
40 votes
14 answers
7k views

Moon that changes color with phase

In a world I am building, I would like to have the moon change color when seen from the planet's surface as it goes through its phases (e.g., the crescent after new moon is blood red, a quarter moon ...
Aliden's user avatar
  • 901
35 votes
7 answers
5k views

Can a radioactive moon affect life on a planet?

This question is meant as a reality check on this answer to The land grows evil and corrupted ... but why? Radioactive moon in a nearly geosynchronous orbit. It slowly kills or alters all life ...
Mołot's user avatar
  • 33.3k
35 votes
6 answers
6k views

What's the smallest reasonable natural planet or moon with Earth-like surface gravity?

We all know that equation for surface gravity is $$ g = \frac{4\pi}{3} G \rho r $$ So if we want Earth-like surface gravity of $ g = 9.81 $, then the equation for radius is $$ r = \frac{3 g}{4\pi G ...
Mołot's user avatar
  • 33.3k
34 votes
12 answers
8k views

How would one design an undetectable nuke to hit the Moon with?

Colonists have set up a viable, long term lunar colony on the near-side of the moon in the mid-21st century. They are quickly reaching total self-sufficiency and the earth governments who sponsored ...
Green's user avatar
  • 52.8k
33 votes
6 answers
8k views

How big could an alien-made object on the far side of the moon become so that discovery still can only happen by accident?

A great way to introduce advanced technology to a story is to have it be of extraterrestrial origin. E.g. have a spaceship crash on earth, or, like I was planning to, put a derelict spaceport on the ...
dot_Sp0T's user avatar
  • 12.1k
33 votes
11 answers
8k views

Where is the best place to park your damaged spaceship, longterm?

Your large spaceship is damaged beyond repair. You manage to get it close enough to a planet so that you can release emergency shuttle craft. You have very little control over the ship and won't be ...
EveryBitHelps's user avatar
32 votes
11 answers
8k views

What skin colour would living permanently on the moon select for?

The context: There is a population of people surviving on a lunar-analogue's surface, descended from the crew of a crashed spaceship. The rest of their society is not relevant to the question, but ...
Ynneadwraith's user avatar
  • 8,066
32 votes
8 answers
7k views

Can we 'beam' energy from the moon?

Really can't believe I have to edit this in, but this question has no bearing on our current use and generation of nuclear energy on Earth. There are dangers to nuclear energy generation, or we would ...
Twelfth's user avatar
  • 24.3k
31 votes
5 answers
11k views

If Sweden was to magically float away, at what altitude would it be visible from the southern hemisphere?

If a chunk of land mass the size and position of Sweden took off and floated away in a straight line, exiting the atmosphere and orbiting earth, at what distance would it be visible from, let's say, ...
Pangolin's user avatar
  • 435
30 votes
12 answers
6k views

How to wrap the Moon in plastic to make her a giant, supported by the atmospheric pressure, greenhouse

Moon's surface is about thirty million square kilometers large. That's a lot of plastic, but no bigger effort than many other terraforming projects we have discussed. Description: A global bubble ...
Ginasius's user avatar
  • 1,346
28 votes
5 answers
7k views

How deep must be a pit on the moon to hold atmosphere at 1ATM on the bottom

In my world I would like to create a pit on the Moon filled with air. How deep would the pit need to be to get 1 ATM of pressure Could the pit maintain the air or would it be lost to space? If it ...
Igor Novelli's user avatar
28 votes
12 answers
3k views

How can spacecraft manufactured on the moon be powered?

Background: The moon has been selected as the base for human space exploration. Rather than ship tonnes of material out of earth's gravity well, interplanetary spacecraft and space stations will be ...
user avatar
27 votes
12 answers
10k views

Would gas giants work as waste disposal sites?

In my novel, the many moons of Jupiter and Saturn have been colonized, but I'm running into some logistical problems - namely, waste disposal. My first instinct was to dump it on-moon; while this is ...
Kabob Maraca's user avatar
27 votes
5 answers
3k views

Can you add a mini moon to Earth?

So we have had multiple questions on having multiple moons and this is another. I did check and didn't find questions that covered this specific setup. I have an earth-like world I am working on, ...
James's user avatar
  • 32.9k
25 votes
10 answers
8k views

How would you build a harbor in a world with *intense* tides?

Long story short, my world is set on a habitable moon of a gas giant, and as a result has some very intense tides (about 5x those of Earth, averaging a few dozen foot difference between high and low ...
morningknight's user avatar
24 votes
5 answers
6k views

What would a habitable moon most probably look like?

We have a pretty good idea of what attributes a planet would need to sustain life and one can imagine how life might develop on a planet, even in difficult environments. I find it extremely difficult ...
Tonio's user avatar
  • 341
24 votes
3 answers
4k views

Realistic sky of an Earth-like moon orbiting a gas giant (length of day and size of celestial bodies)

I'm trying to work out what the sky looks like on an Earth-like moon, in particular the length of day and apparent size of the other celestial bodies: the gas giant's size, the gas giant's other moon'...
Udon Nomaneim's user avatar
23 votes
7 answers
7k views

How big can a moon be where you can physically jump out of its orbit, to its planet?

So, imagine a team of space marines, fighting some sort of space bug zombies on a planet's moon. Things are going pretty bad for them, and the last surviving protagonists are running for their lives. ...
DaaaahWhoosh's user avatar
22 votes
13 answers
4k views

Terminology for 24 hour wake-sleep cycle on world with longer dark-light cycle?

Take the Jovian moon Ganymede as a real-world example. It has an orbital period of ~7 days around Jupiter, which is effectively its day and its year simultaneously. My characters will need the words ...
Pasqueflower's user avatar
  • 1,178
22 votes
14 answers
5k views

Always a full Moon for the Emperor - Can this be achieved with solar panels and LEDs?

The Emperor of the World wants there always to be a full moon. His Scientific Advisor (the SA) comes up with a plan. He plans to cost out the venture, hand it over to the Keeper of the Treasury who ...
chasly - supports Monica's user avatar
22 votes
15 answers
4k views

How can a spaceship unknowingly interfere with tides on a planet?

I've asked before about my polytheists with competing moon gods. I now have a better understanding of how tides -- a very visible manifestation of lunar influence -- work with multiple moons (thanks),...
Monica Cellio's user avatar
21 votes
7 answers
8k views

The Moon turns into a black hole of the same mass -- what happens next?

If there were a black hole orbiting an inhabited planet, with the gravity of a typical moon (e.g our moon, orbiting a similarly weighted planet to ours), what practical differences would arise when ...
zevythegreat's user avatar
21 votes
5 answers
4k views

Would a planet appear to wax and wane as observed from its moon?

Assuming that the observer is on the moon for a full lunar cycle, would the appearance of the planet wax and wane, would the moon's shadow occlude the planet during an eclipse while on the moon?
Cantabile's user avatar
  • 211
21 votes
1 answer
3k views

Plausibility of a gas giant moon

Is it plausible for a mini-Neptune to form around another gas giant? How big would the main gas giant be to accomodate such a moon?
asteroidbelt's user avatar
21 votes
3 answers
3k views

That's no moon! It's a space station! How big can a space ship be before it collapses on itself?

Now a solid body of rock will collapse itself to a round shape when it hits about 600 km in diameter (400 km for ice). Now, the Second Death Star is estimated to be between 160 and 900 km. How big can ...
bowlturner's user avatar
  • 49.2k
21 votes
3 answers
4k views

Reality Check: Habitable moon around earth-like planet

For a complex world-building scenario I want a habitable moon orbiting a habitable earth-like planet. The habitable moon should allow for flora, fauna and landscape as similar to earth as possible. ...
DerGreif's user avatar
  • 591
21 votes
1 answer
2k views

Can a habitable moon rely on the magnetosphere of its parent planet for radiation protection?

Science-based answers, please. Key points: the main concern is radiation protection for sustainability of human life (and accompanying plant and animal life ecosystems, whether earth-like or not). ...
Harthag's user avatar
  • 4,133
20 votes
7 answers
6k views

How would a planet-sized computer power receive power?

Imagine: A Kardashev Type I civilization mainly resides on a planet analogous to Earth, with one moon, analogous to Earth's moon. Eventually, the society grows so complex that machines filling space ...
Zxyrra's user avatar
  • 20.6k
20 votes
3 answers
4k views

Tidally locked gas giant moon - brightness of the gas giant

Imagine a tidally locked gas giant moon, which is otherwise earth-like. One side of the moon will have a huge planet constantly hovering in the sky (24 hour day/night cycle with a Jupiter-sized ...
Korvas's user avatar
  • 803
20 votes
1 answer
3k views

How does one calculate the tidal heating of a satellite?

I've been searching for hours, and most formulas I can find use complex/imaginary numbers or variables that I don't know or can't find out (such as the imaginary part of the planet's love number, ...
Alexader Ferguson's user avatar
19 votes
9 answers
5k views

What kind of event, if any, would knock the moon off its orbit, without destroying it?

I am recalling the Space:1999 nuclear waste containment explosion; this has been criticized because such an explosion would have actually destroyed the moon. I am curious for events that could happen ...
guido's user avatar
  • 1,500
19 votes
4 answers
2k views

Earth-like Moon around the Gas Giant. Eclipse length?

Worldbuilder in dire need! I'm trying to figure out the eclipse length of a habitable Earth-like moon that is rotating around a gas giant. The story that I work on is centered on the Earth-like moon, ...
Jotunn's user avatar
  • 616
19 votes
4 answers
753 views

Making doomsayers right - a moon(s), planet alignment that matters

Considering our topic challenge, and the fantastic eclipse last Sunday a question came to me. Could there be a stable (relatively speaking) planetary system where a(n) eclipse/alignment would ...
James's user avatar
  • 32.9k
18 votes
25 answers
5k views

What might cause a civilization to be unable to colonize a large moon but live in space stations around it instead?

In my world a moon is reached and colonised but only in space stations for a long time. They gain the ability to reach the surface and then story happens. It needs to be something that can be bypassed ...
Topcode's user avatar
  • 2,285
18 votes
8 answers
6k views

Is a moon inside a hollow Earth possible?

The Hollow Earth theory is/was a pseudoscientific idea that our world is actually on the inside of a large sphere. The "sky" points inward towards the center, where the "Sun" (a light source) is, ...
HDE 226868's user avatar
  • 101k
18 votes
5 answers
7k views

By what mechanism could a planet be locked into permanent solar eclipse?

I've got an image in my head of a world where it's just normal that the star is black with a golden halo around it - in other words, where the planet is in a state of perpetual solar eclipse. Are ...
Nerrolken's user avatar
  • 3,568
17 votes
7 answers
5k views

How to flood the entire lunar surfaces?

Given that the surface gravity on the Moon is a fraction of Earth and there is virtually zero atmospheric pressure but I still want to wet our beloved moon with whatever liquid that is known to ...
user6760's user avatar
  • 47.9k
17 votes
3 answers
6k views

Are moons always the same colour?

When viewed from their planet, are moons always the same colour as ours? Or is there a variation? What other colours might be possible and what causes the differences in colour?
Jaz's user avatar
  • 335
17 votes
7 answers
2k views

Colony on the moon - how fast can Santa deliver?

I sometimes tell my kid that when he grows up, he might be living on the moon. Last night he was worried that Santa won't be able to bring him presents there. To which I replied that sure, Santa can ...
Nahshon paz's user avatar
  • 6,088
17 votes
3 answers
1k views

Can we breathe the moon's crust?

According to this answer to what the moon is made of, the moon's crust is, among other things, 43% oxygen. Assuming we were to go back to the moon within the next couple of years with the goal of ...
Kromey's user avatar
  • 8,495
16 votes
13 answers
14k views

Is stealing the moon actually possible?

I'm writing a heist story set in the near future. The goal of my main protagonists is to actually steal the Moon. The budget of their escapade is not a variable; they will get this done however ...
Gideon Ebeling's user avatar
16 votes
17 answers
5k views

What would cause a moon to become much brighter only a few times a year?

I initially wanted to create a culture that used tides to tell the seasons, I'm sure I still can, but a question on here (I can no longer find it) made me wonder if I could set up a world where one of ...
AncientSwordRage's user avatar
16 votes
10 answers
8k views

Could humans alter the moon's orbit significantly with current technology?

A terrible virus has made most of the populations and government officials of the largest superpowers on Earth stark, raving mad, without depriving them of their intelligence. They have decided that ...
Fiksdal's user avatar
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